Concorde....

Both European airlines operated demonstrations and test flights from
1974
onwards. The testing of Concorde set records which are still not
surpassed; it undertook 5,335 flight hours in the prototype,
preproduction, and first production aircraft alone. A total of 2,000
test
hours were supersonic. This equates to approximately four times as many
as
for similarly sized subsonic commercial aircraft.

Clive

And the ratio of hours of revenue flight for the two are what then?
And when you combine the two, the ratio of revenue flight hours to
test-flight time is what?

Concorde had been the safest working passenger airliner in the world
according to passenger deaths per distance travelled, although the Boeing
737 fleet acquires more passenger miles and service hours in one week than
the Concorde fleet acquired in the course of its entire service career.
The crash of the Concorde was the beginning of the end of its career.

Good enough?

Clive